Crystalline Sponge Gallery

G037 · Anthraquinone glycoside

Aloin A

C21H22O9 · 418.40 g mol−1

First crystal structure · Angewandte Chemie International Edition 2026 · compound 26 →

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INTERACTIVE 3D STRUCTURE

Explore Aloin A in its crystalline sponge

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CHONCage
2D chemical structure of Aloin A
Aloin A · 2D chemical structure
3D crystal structure of Aloin A determined by the crystalline-sponge method
Aloin A · crystalline-sponge guest structure
Aloin A inside a crystalline sponge coordination cage
Aloin A · coordination-cage host–guest structure

Aloin A resolved by the crystalline-sponge method.

A historic Aloe natural product whose C-glycoside stereochemistry challenged isolation, synthesis and crystallization.

Molecular formula
C21H22O9
Molecular weight
418.40 g mol−1
CCDC accession
2463105 ↗
Host
Pd6L4 cage
Study
Angew. Chem. 2026
Compound in publication
26

MOLECULAR HISTORY

From nineteenth-century “aloine” to a definitive molecular structure

Aloin was isolated as the crystalline bitter principle of aloes long before modern spectroscopy. Its A and B forms interconvert, while the anthrone C-glycoside architecture presents an unusually demanding stereochemical and synthetic problem.

  1. 1851

    A crystalline principle from aloes

    Thomas Smith and John Stenhouse described the isolation and purification of “aloine” from Barbados aloes, establishing one of the earliest chemically defined Aloe constituents.1

  2. 1989

    Aloin A and B configurations established

    Rauwald, Lohse and Bats established the configurations of the two diastereomeric C-glucosylanthrones, clarifying the relationship between Aloin A and Aloin B.2

  3. 2010

    Synthetic access to the C-glycoside framework

    A benzyne–furan strategy produced an advanced analog of 5-hydroxyaloin A and highlighted the difficulty of constructing the anthrone C-glycosidic bond.3

  4. 2025

    First total synthesis of aloin

    Sequential regioselective Diels–Alder reactions connecting silylbenzynes and a stannylfuran enabled the first reported total synthesis of aloin.4

  5. 2026

    First definitive crystallographic structure

    The crystalline sponge delivered the first definitive crystallographic view of Aloin A and established its absolute configuration directly.5

WHY THIS STRUCTURE MATTERS

More than 170 years after aloin entered chemical literature, Aloin A still lacked a definitive native-form crystal model. The crystalline-sponge structure makes its full three-dimensional configuration directly visible.

References

  1. Stenhouse, J. “On Aloine, the Crystalline Cathartic Principle of Barbadoes Aloes.” Pharm. J. Trans. 1851. Historical text ↗
  2. Rauwald, H. W.; Lohse, K.; Bats, J. W. “Establishment of Configurations for the Two Diastereomeric C-Glucosylanthrones Aloin A and Aloin B.” Angew. Chem. Int. Ed. 1989, 28, 1528–1529. DOI 10.1002/anie.198915281 ↗
  3. Procko, K. J.; Li, H.; Martin, S. F. “An Approach Toward the Total Synthesis of 5-Hydroxyaloin A.” Org. Lett. 2010, 12, 5632–5635. DOI 10.1021/ol102318k ↗
  4. Moriyama, S.; Emi, Y.; Nosaki, T.; et al. “Total Synthesis of Aloin via Regioselective Diels–Alder Reactions Connecting Two 3-Silylbenzynes and 2-Stannylfuran.” Synlett 2025, 36, 1413–1417. DOI 10.1055/a-2542-3481 ↗
  5. He, W.; Takezawa, H.; Fujita, M. Angew. Chem. Int. Ed. 2026, 65, e202524615. DOI 10.1002/anie.202524615 ↗

SOURCE PUBLICATION

Second-Generation Crystalline Sponges Enabling Consistent Structure Analysis Under Standardized Conditions for Diverse Molecules

Angewandte Chemie International Edition 2026

DOI 10.1002/anie.202524615 ↗